Sling lock



Nov. 5, 1940. .R. THIRLWELL SLING LOCK Filed DeC. 7, 1937 ROBERT THIRLWELLIY BY I Y "7 I 5 ATTORNEYS Patented Nov. 5, 1940 SLING LOCK Robert Thirlwell, Newcastle-on-Tyne, England Application December 7, 1937, Serial No. 178,605 In Great Britain December 15, 1936 This invention relates to sling locks of the kind comprising a sleeve or barrel through which the sling is adapted to be passed and means on the outside of said sleeve for attaching the end of An example of such a sling lock is described and shown in my patent specithe sling thereto.

fication No. 1,882,167.

According to a proposal for use with a hookless chain the chain passed through a vertical bore in a boss-like portion of a substantially rectangular block with square edges and having a. system of vertical and horizontal recesses or grooves for the reception of specially formed links at the end of the chain. In the raising of loads whose length is considerably greater than its thicknessfor example a bundle of rods or tubesthe load generally tilts and sometimes where it has to be lowered through confined spaces it is necessary to grip the load near the end to cause it to assume a position nearer the In such positions the positive support of the sling becomes less effective the nearer the load is to the vertical, so that the frictional grip of the sling becomes the vertical than the horizontal.

sole means for holding the load.

While with a lock having its lower edges square a certain increase of strength of grip does take place as the load tilts more and more towards the vertical it has been found in practice not to give a strong enough grip. Hence the object of the present invention is to provide means whereby as the load tilts more and more from the horizontal the grip exerted on it is increased by the maximum amount.

sling about the load.

The invention will now be described by way of example with reference to the accompanying drawing.

In the said drawing:

Fig. l is a section on the line I-I of Fig. 2 of a sling lock for use with a chain or rope having an eye at its end.

Fig. 2 is an end elevation of Fig. Fig. 3 is a plan of Fig. 1.

1 Claim.

. Fig. 4 is a section of a modified form of the invention on the line IV--IV of Fig. 5 of a Sling lock for use with a chain or rope having a hook at its end.

Fig. 5 is an end elevation of Fig.4. 5 Fig. 6 is a plan of Fig. 4; Referring more particularly to Figs. 1 to 3, the sling lock is made in a single block which may be cast or forged, or made of separate portions welded together, the said block comprising 10 a cylindrical sleeve I (hereinafter referred to as the chain sleeve) and a flat portion 2 projecting radially in plan therefrom and extending longitudinally for the length'of the said chain sleeve, the fiat portion having a transverse hole 2a formed therein at its lower portion to receive the sling hook 3 indicated in chain lines in Fig. 1.

The upper and lower ends of the chain sleeve l are flanged at 4 to impart strength at these points and to provide on the lower face of the sleeve on either side of the plane containing the sleeve axis and the flat portion 2 a relatively large curved section so that, as shown diagrammatically in Fig. 2 the tilting axis la. of the load moves towards the outside of the sleeve l and thus causes the resultant moment of the load about the said axis to increase so that a further increase of grip is imposed on that which would be exerted if the tilting axis were a right angle edge. The chain sleeve ends are of bell shape to ensure that the chain enters and leaves the sleeve in a gradual curve so as to avoid undue friction.

Webs 5 are formed at the lower portion of the sling lock between the chain sleeve I and the flat portion 2 to provide projections which maintain the tilting axis of the load substantially transverse to the plane containing the sling in the event of the load tending to tilt.

Above the eye 20. a boss is formed to receive a transverse threaded bore with which engages a threaded plug 6, the said threaded bore intersecting the cylindrical bore of the chain sleeve l. The plug 6 abuts against a transverse bar '3 substantially of D-section, passing through transverse slots 8 extending into the chain sleeve 1, the bar 1 being reduced at its ends to receive nuts 9 which maintain it against end movement. Hence, by turning the plug 6 the bar I may be moved inwards until it abuts against the chain (shown in dot and dash lines) so that the sling lock may be positively locked against the chain.

The sling lock is applied to the sling chain by threading the latter through the chain sleeve from beneath. When not in use the sling lock rests on top of the crane hook. All that is necessary to sling a load is to pass the sling chain around the load, at the same time sliding the chain hook 3 into the sling lock eye 2a. The weight of the load causes the sling lock to slide down the chain and abut firmly against the load, there being practically no friction between the chain and the chain sleeve bore,

With this arrangement the degree of adjustment of the sling about the load is infinite so that whatever be the dimension or shape of the load the grip is taken up automatically by the sling without recourse being had to striking the sling as has to be done with chain or wire slings as used without the sling lock. Further, with chain slings as used hitherto the degree of adjustment of the size of the sling is arbitrary and is limited to steps depending on the length of the individual links with which the hook is engaged.

While the invention has been described as especially adapted for use with chains, obviously it can be applied to ropes and cables.

By making the sling lock of suitable Weight, the usual weight suspended from the end of the crane chain may be dispensed with.

Obviously instead of the eye being formed in the fiat portion, the lower portion of this latter may take the form of a hook or an open eye, such as is shown in Figs. 4 to 6.

Figs. 4 to 6 show a simpler form of the invention in which the clamping means are dispensed with. According to this form the sling lock comprises a chain sleeve H and an outwardly directed hook 9, while a shield I0 is formed above lying entirely in a plane. perpendicular to said axis, a flat portion projecting radiallyin plan from said sleeve, said flat portion extending longitudinally throughout the length of the sleeve, and means on said flat portion for attaching thereto the end of the sling, the lower portion of said sleeve on both sides of a plane passing through the axis of the sleeve and the attaching means having an outwardly extending fla-nge'whereby the thickness of said lower portion of the sleeve is considerably increased, webs at the lower portion of the sling lock between the sleeve and said flat portion merging with said thickened portion of the sleeve, the outer edges of said Webs on opposite sides of said fiat portion being'tangential to the outer diameter of said flange, the outer edges of said flange and said webs being rounded so that in manipulating a load, as the angle between the plane of the lower end face of the sleeve and the load increases, a relative rotation between the sleeve and load takes place about said rounded flange and webs, causing the point of engagement of the sling lock and load to'be displaced laterally a greater distance from the axis of the sleeve to increase the grippingforce of the sling about the load.

ROBERT THIRLWELL. 

